Effect of super-high pressure on microstructure and mechanical properties of Mg97Zn1Y2 alloys

Super-high pressure (SHP) technique plays an increasing role in the fields of materials science and engineering. Herein, the Mg97Zn1Y2 alloy was heat-treated under SHP (6 GPa) by cubic-anvil large-volume press with six rams for 2 h in the temperature range of 500-1200 °C. The microstructure and mechanical properties were investigated. The results indicated that the as-cast sample consists of α-Mg equiaxed dendrites and continuous lamellar long period stacking ordered (LPSO) phase in grain boundaries. After the SHP treatment, the LPSO phase is gradually replaced by eutectic phase (Mg,Zn)3Y with increasing temperature. The microhardness and strength of sample prepared at 1100 °C under SHP treatment are significantly improved compared with the as-cast one at room temperature. The improved mechanical behaviors are mainly attributed to LPSO phase kink-banding strengthening at low temperature and the precipitation strengthening of a large amount of fine (Mg,Zn)3Y particles at high temperature after SHP treatment. It reveals the SHP is an effective approach to prepare high performance Mg alloys.